STRAIN MEASUREMENTS ON EIGHT FULL-SCALE WING CENTER SECTIONS.
NATIONAL AERO- AND ASTRONAUTICAL RESEARCH INST AMSTERDAM (NETHERLANDS)
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For an investigation on the equivalence of random and programmed fatigue loads eight full-scale wing center sections were tested. Each fatigue test was preceded by a static test to check the similarity of the stress distribution in all tension skins. In the report the results of these static tests are presented and an analysis of the trends observed is given. The maximum load in the static test was only slightly beyond the mean load of the fatigue tests. The following observations were made a The strain measurements made on port and starboard of the tension skin are in good agreement b The same applies to the strain measurements made on all eight tension skins at the same location. c At the same location on different tension skins the average value of the standard deviation was 2. The scatter is mainly due to the measurement techniques and not to differences between the tension skins. d Secondary bending, although small, increased somewhat the scatter of the results. e The effect of fatigue loading on the output of the strain gages was very small, despite the high fatigue loading which induced failure of many gages. Author